Method for reducing plate out of aqueous coating compositions

ABSTRACT

A method of reducing plate out onto metal surfaces of aqueous latexes and coating compositions, including paints such as traffic paints, the method comprising employing a composition comprising a triazole. The method produces less plate out onto process metal surfaces compared to coatings prepared from similar triazole-free compositions.

This application is a National Stage application under 35 U.S.C. 371 ofPCT/US2008/002071, and published as WO 2008/100607 on Aug. 21, 2008,which claims priority to U.S. Provisional Application Ser. No.60/901,445 filed Feb. 15, 2007.

FIELD OF THE DISCLOSURE

Embodiments of the present disclosure relate to the reduction of plateout of aqueous latex-containing compositions, such as a latex or a latexpaint.

BACKGROUND

Fast hardening, also referred to as fast drying or quick setting,aqueous latex-based traffic paints are currently in wide use. Oneadvantage of these water-based paints is that they contain low amountsof volatile organic compounds compared to solvent based paints. However,the chemistry involved in the fast hardening mechanism of these paintscan lead to situations in which the paint plates out on processsurfaces, such as spray equipment. Traffic paint typically is applied asa spray from a moving vehicle. Plate out on process metal surfaces, suchas the surfaces of the spray nozzle of the vehicle, can result in lossof productivity. Since the wide acceptance of aqueous traffic paints inthe late 1980's, this problem has existed for traffic paint users,especially when using paints containing polyamine or polyimineadditives, such as polyethyleneimine, in combination with a metalprocess surface where the metal is not stainless steel.

It would be desirable to have an aqueous latex-containing composition,such as a traffic paint, in which the plate out problem would besubstantially reduced.

SUMMARY

Embodiments of the present disclosure include a method includingapplying as a coating a composition including a triazole as a plate outreducing agent, the composition further including:

(a) an anionically stabilized aqueous dispersion of a copolymer, thecopolymer comprising in polymerized form a polymerization mixturecomprising two or more ethylenically unsaturated monomers wherein, basedon the total weight of all ethylenically unsaturated monomers in thepolymerization mixture, from 0 to about 4 weight percent of the monomersare alpha, beta-ethylenically unsaturated aliphatic carboxylic acidmonomers;

(b) an effective amount of a polyimine or polyamine; and

(c) an effective amount of a volatile base;

wherein the amount of triazole is from about 0.01 to about 5 weightparts, based on 100 weight parts solids of the copolymer of (a).

In another aspect, embodiments of the present disclosure include amethod including incorporating into an aqueous latex or paint an amountof a triazole that is sufficient to provide a Plating Reduction onto azinc plated steel lag screw of at least 10%.

Embodiments of the present disclosure also involve the use of a triazoleas a plate out reducing agent in a fast hardening aqueous coatingcomposition.

The above summary of the present disclosure is not intended to describeeach disclosed embodiment or every implementation of the presentdisclosure. The description that follows more particularly exemplifiesillustrative embodiments. In several places throughout the application,guidance is provided through lists of examples, which examples can beused in various combinations. In each instance, the recited list servesonly as a representative group and should not be interpreted as anexclusive list unless explicitly stated as such.

DEFINITIONS

As used herein, “a,” “an,” “the,” “at least one,” and “one or more” areused interchangeably. The terms “comprises,” “includes,” and variationsthereof do not have a limiting meaning where these terms appear in thedescription and claims. Thus, for example, a fast hardening aqueouscoating composition that includes an anionically stabilized aqueousdispersion of “a” copolymer can be interpreted to mean that theanionically stabilized aqueous dispersion includes “one or more”copolymers.

As used herein, the term “and/or” means one or all of the listedelements.

As used herein, the term “dry” means in the substantial absence of waterand the term “dry basis” refers to the weight of a dry material.

For the purposes of the present disclosure, the term “copolymer” means apolymer derived from more than one species of monomer.

As used herein, “Tg” is an abbreviation for glass transitiontemperature.

As used herein “ml” is an abbreviation for milliliter(s).

As used herein “mm” is an abbreviation for millimeter(s).

As used herein “mil” is an abbreviation for a unit of length equal to1/1000 of an inch.

As used herein “° C.” is an abbreviation for degrees Celsius.

As used herein “g” is an abbreviation for gram(s).

As used herein, “aryl” refers to a compound whose molecules have thering structure characteristic of benzene, naphthalene, phenanthrene,anthracene, etc. (i.e., either the 6-carbon ring of benzene or thecondensed 6-carbon rings of the other aromatic derivative).

As used herein, “halogen” refers to one of the electronegative elementsof group VIIA of the periodic table (fluorine, chlorine, bromine,iodine, etc.).

Also herein, the recitations of numerical ranges by endpoints includeall numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2,2.75, 3, 3.80, 4, 5, etc.).

For the purposes of the present disclosure, the term “room temperature”means 20° C. to 25° C.

As used herein, the term “process metal surface” means a metal surfacethat the composition comes into contact with during use or preparation.

As used herein, the term “triazole” includes the compound in salt and/ornon-salt form.

DETAILED DESCRIPTION

The method of the present disclosure includes preparing a compositionthat includes an aqueous latex, a volatile base, a polyimine and/or apolyamine, and a triazole.

A triazole is employed in embodiments of the present disclosure in anamount that is sufficient to lessen the amount of plate out onto aprocess metal surface as determined by the Plate Out Test describedherein. Advantageously, the amount of triazole employed is from about0.01 to about 5 weight parts, based on 100 weight dry parts of acopolymer including in polymerized form a polymerization mixturecomprising two or more ethylenically unsaturated monomers where, basedon the total weight of all ethylenically unsaturated monomers in thepolymerization mixture, from 0 to about 4 weight percent of the monomersare alpha, beta-ethylenically unsaturated aliphatic carboxylic acidmonomers solids. The amount of triazole employed can also be from about0.1 to about 3 parts, based on 100 weight parts solids of the copolymerof the anionically stabilized aqueous dispersion. In addition, in someembodiments, the amount of triazole employed can be from about 0.25 toabout 1.5 parts.

In various embodiments, the triazole comprises a compound of thestructure:

wherein R₁, R₂, R₃, and R₄ are independently selected from hydrogen,alkyl, aryl, halogen, amino, alkylamino, dialkylamino, hydroxyl, nitro,acetamido, trifluoromethyl, sulfonic acid, and cyano.

Examples of suitable triazoles include benzotriazole,5-methyl-1H-benzotriazole (tolyltriazole),7-acetamido-5-methyl-1,2,3-benzotriazole,5-acetamido-5-methyl-1,2,3-benzotriazole,5-amino-6-methyl-1,2,3-benzotriazole,7-amino-5-methyl-1,2,3-benzotriazole,6-methyl-4-nitro-1,2,3-benzotriazole, 4,6-dimethylbenzotriazole,5-butyl-4-nitro-1H-benzotriazole, 4-chloro-5-methyl-1H-benzotriazole,5-chloro-6-methyl-1H-benzotriazole,7-hydroxy-5-methyl-1H-benzotriazole-4,6-dicarbonitrile,5-hexyl-1H-benzotriazole, 5-methyl-1H-benzotriazole-4-amine,6-methyl-1H-benzotriazole-5-ol, 5-ethyl-6-nitro-1H-benzotriazole,5-methyl-6-nitro-1H-benzotriazole,4-bromo-5,6-dimethyl-1H-benzotriazole, 5-ethenyl-1H-benzotriazole,4,5,6,7-tetramethyl-1H-benzotriazole,5-(1,1,4-trimethylpentyl)-1H-benzotriazole,5-(1,1-dimethylpropyl)-1H-benzotriazole,5-(1,1,3,3-tetramethylbutyl)-1H-benzotriazole,5-(1,1-dimethylethyl)-1H-benzotriazole, 5-octyl-1H-benzotriazole,4,5-dimethyl-1H-benzotriazole,5-chloro-6-methyl-4-nitro-1H-benzotriazole,5,6-dimethyl-4-nitro-1H-benzotriazole,5-methyl-4,6-dinitro-1H-benzotriazole,5-methyl-4-nitro-1H-benzotriazole,5-methyl-4-trifluoromethyl-1H-benzotriazole,5-methyl-6-trifluoromethyl-1H-benzotriazole,5-butyl-1H-benzotriazole-4-ol, 5-methyl-1H-benzotriazole-4-ol,5,6-dimethyl-1H-benzotriazole, 5-ethyl-1H-benzotriazole,5-dodecyl-1H-benzotriazole, and 5-butyl-1H-benzotriazole, withbenzotriazole and tolyltriazole being preferred examples. Mixtures oftriazoles can also be employed.

It is understood that the triazole may be present in the neutral form orsalt form, and that these forms are readily interconvertible by wellknown simple procedures. The triazole can be employed either in saltform or non-salt form, or as a mixture of both. In some embodiments, themethod can employ a composition in which the triazole employed may havea pH of over 7, and in such a situation at least part of the triazolemay be in salt form, e.g. the sodium or ammonium salt of the triazole.Accordingly, as used herein, the term “triazole” includes the compoundin salt and/or non-salt form.

The process of the present disclosure employs at least one syntheticlatex. A synthetic latex, as is well known, is an aqueous dispersion ofpolymer particles prepared by emulsion polymerization of one or moremonomers. The latex can have a monomodal or polymodal, e.g. bimodal,particle size distribution. Latexes used in fast hardening applicationsare well known to those skilled in the art, and many of such latexes arecommercially available. Mixtures or blends of latexes can also beemployed.

In various embodiments, the polymer of the latex can be a copolymer. Thelatex may contain a single copolymer or more than one copolymer.Advantageously, in some embodiments, the polymer of the latex has aglass transition temperature (Tg) of from about −50° C. to about 100° C.

In various embodiments, copolymers that are useful alone, as opposed tothose more useful in a blend, can have a Tg of no lower than about −10°C., preferably at least about 0° C. In some embodiments, the Tg of thecopolymer is no higher than about 50° C., and in some examples, the Tgcan be up to about 40° C. The generally preferred range is from about 0°C. to about 40° C. In the present disclosure, the Tg of the copolymercan be determined by differential scanning calorimetry (DSC).

While a wide range of monomeric compositions ate useful for thecopolymeric component of the fast hardening aqueous coating composition,in some embodiments it is preferred that the copolymer is uncrosslinkedby virtue of there being no crosslinking monomers present in the groupof ethylenically unsaturated monomers present in the polymerizationmixture from which it is prepared. That is, it is desirable that thecopolymer be produced by polymerization in the absence of crosslinkingmonomers or some other crosslinking agent. In addition, in suchembodiments, it is desirable that there be no other source of covalentcrosslinking in the fast hardening aqueous coating composition.

In alternative embodiments, it can be desirable for the copolymer to belightly crosslinked. This may be accomplished by the inclusion in thepolymerization mixture from which the copolymer is prepared of a monomerwhich is multifunctional and of known utility as a crosslinker, such as,for example, divinyl benzene or allyl (meth)acrylate. In suchembodiments, the content of crosslinking monomers in the copolymer canbe limited to no more than about 2 weight percent, preferably from 0.001to 2 weight percent, more preferably from 0.01 to 1.5 weight percent,and still more preferably from 0.1 to 1 weight percent, where the weightpercentages are based on the total weight of monomers in thepolymerization mixture.

A wide variety of monomers may be used to prepare copolymers suitablefor use in the method of the present disclosure. (Meth)acrylatecopolymers comprising primarily (meth)acrylate monomers are onedesirable type of copolymer.

For the purposes of the present disclosure, the term “(meth)” indicatesthat the methyl substituted compound is included in the class ofcompounds modified by that term. For example, the term (meth)acrylicacid represents acrylic acid and methacrylic acid.

As used herein the term “(meth)acrylate copolymer” means a copolymerwhich contains in polymerized form at least 80 weight percent(meth)acrylate monomers and (meth)acrylic acid monomers, where theweight percentage is based on the total weight of monomers in thepolymerization mixture. In some embodiments, the copolymer can containin polymerized form at least 90 weight percent (meth)acrylate monomersand (meth)acrylic acid monomers, while even more preferred are theembodiments where the copolymer contains in polymerized form at least 95weight percent (meth)acrylate monomers and (meth)acrylic acid monomers.

In various embodiments, the copolymer can be a pure (meth)acrylate, or apure (meth)acrylate except for the inclusion of a non-(meth)acrylateseed therein. These copolymers consist essentially of (meth)acrylatemonomers, or of (meth)acrylate monomers and (meth)acrylic acid monomers.

The term “(meth)acrylate monomers” is meant to include those monomerswhich are used to prepare the (meth)acrylate copolymers which aresuitable for use in the method of the present disclosure. Includedtherein are conventionally known acrylates, such as, for example, alkylesters of acrylic acid, represented by the formula CH₂═CHCOOR, andmethacrylic acid, represented by the formula CH₂═CCH₃COOR, where R is ahydrocarbyl or a substituted hydrocarbyl group containing from 1 to 16carbon atoms. The term “(meth)acrylic acid monomers” is meant to includeacrylic acid, methacrylic acid, and/or substituted derivatives thereof.

The term “(meth)acrylate monomers” as used herein is meant also toinclude the monovinyl acrylate and methacrylate monomers. The(meth)acrylates can include esters, amides, and substituted derivativesthereof. Generally, the preferred (meth)acrylates are C₁-C₈ alkylacrylates and methacrylates.

Examples of suitable (meth)acrylates include methyl acrylate, ethylacrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octylacrylate and isooctyl acrylate, n-decyl acrylate, isodecyl acrylate,tert-butyl acrylate, methyl methacrylate, butyl methacrylate, hexylmethacrylate, isobutyl methacrylate, isopropyl methacrylate as well as2-hydroxyethyl acrylate and acrylamide. The preferred (meth)acrylatesare methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexylacrylate, octyl acrylate, isooctyl acrylate, methyl methacrylate andbutyl methacrylate. Other suitable monomers include lower alkylacrylates and methacrylates including acrylic and methacrylic estermonomers: methyl acrylate, ethyl acrylate, n-butyl acrylate, t-butylacrylate, 2-ethylhexyl acrylate, decyl acrylate, isobornyl acrylate,methyl methacrylate, ethyl methacrylate, n-propyl methacrylate,isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate,sec-butyl methacrylate, cyclohexyl methacrylate, isodecyl methacrylate,isobornyl methacrylate, t-butylaminoethyl methacrylate, stearylmethacrylate, glycidyl methacrylate, dicyclopentenyl methacrylate, andphenyl methacrylate.

Monomers suitable for use as components in polymers are often classifiedas “hard” or “soft” monomers, depending upon the glass transitiontemperature (Tg) of the homopolymer prepared from the monomer. As usedherein, a hard monomer is characterized as having a Tg greater than 40°C. for its homopolymer, while a soft monomer is characterized as havinga Tg of 40° C. or less for its homopolymer. A preferred hard(meth)acrylate monomer is methyl methacrylate.

The soft non-functional (meth)acrylate monomers have the formula:

wherein R₁ is selected from the group consisting of hydrogen and methyl,and R₂ is an alkyl group, preferably having up to about 15 carbon atoms.As used herein, the term “alkyl” means cyclic and acyclic saturatedhydrocarbon groups that can be either branched or unbranched. Exemplarysoft, non-functional acrylic monomers include, but are not limited to,butyl acrylate, isobutyl acrylate, ethylhexyl acrylate, isodecylmethacrylate, lauryl methacrylate, and tridecylmethacrylate. Butylacrylate is a preferred soft, non-functional monomer.

Suitable non-ester monomers which are sometimes classified with the(meth)acrylates are the nitriles. A preferred nitrile monomer isacrylonitrile.

While some embodiments of the (meth)acrylate copolymer of the presentdisclosure may contain up to about 5 weight percent of other comonomerswhich are not (meth)acrylate monomers, where the weight percentage isbased on the total weight of monomers in the polymerization mixture,other embodiments may contain as other comonomers as much as 10 weightpercent or even as much as 20 weight percent of monomers which are not(meth)acrylate monomers. Other monomers that are useful in thesecopolymers include vinyl aromatic monomers, aliphatic conjugated dienemonomers, monoethylenically unsaturated carboxylic acid monomers, vinylacetate monomer, vinylidene halide monomer, and vinyl halide monomer. Insome other copolymers suitable for use in the present disclosure, themonomers of the polymerization mixture include from about 1 to about 40weight percent of one or more (meth)acrylate monomers.

As used herein, “vinyl aromatic monomers” are defined as organiccompounds containing at least one aromatic ring and at least onealiphatic-containing moiety having vinyl unsaturation; provided, howeverthat this term is not intended to cover a triazole. Illustrative vinylaromatic monomers include styrene, p-methyl styrene, methyl styrene,o,p-dimethyl styrene, o,p-diethyl styrene, p-chlorostyrene, isopropylstyrene, t-butyl styrene, o-methyl-p-isopropyl styrene,o,p-dichlorostyrene, and mixtures thereof. The preferred vinyl aromaticmonomers are styrene and vinyltoluene; and due to its commercialavailability and low cost, styrene is the more preferred vinyl aromaticmonomer.

The term “conjugated diene monomer”, as used herein, is meant to includecompounds such as 1,3-butadiene, isoprene, 1,3-pentadiene,2-ethyl-1,3-butadiene, and 4-methyl-1,3-pentadiene,2-methyl-1,3-butadiene, piperylene (1,3-pentadiene), and otherhydrocarbon analogs of 1,3-butadiene. The preferred alkadiene monomer is1,3-butadiene. Other monomers inclusive as aliphatic conjugated dienesare halogenated compounds, such as, for example, 2-chloro-1,3-butadiene.

The monomers of the vinyl group, such as, for example, “vinylidenehalides” and “vinyl halides”, are suitable for inclusion in thecopolymer of the present disclosure, and include, for example,vinylidene chloride and vinyl chloride, which are highly preferred.Vinylidene bromides and vinyl bromide can also be employed. Anothervinyl monomer within the vinyl group is vinyl acetate.

Suitable alpha, beta-ethylenically unsaturated aliphatic carboxylic acidmonomers are monoethylenically unsaturated monocarboxylic, dicarboxylic,and tricarboxylic acids having the ethylenic unsaturation alpha-beta toat least one of the carboxyl groups and similar monomers having a highernumber of carboxyl groups. It is understood that the carboxyl groups maybe present in the acid or salt form (—COOM in which M represents acation such as ammonium, hydrogen, or a metal such as, for example,sodium or potassium) and are readily interconvertible by well knownsimple procedures.

Specific examples of the alpha, beta-ethylenically unsaturated aliphaticcarboxylic acids are acrylic acid, methacrylic acid, fumaric acid,itaconic acid, maleic acid, aconitic acid, and various alpha-substitutedacrylic acids such as alpha-ethacrylic acid, alpha-propyl acrylic acid,and alpha-butyl acrylic acid. Highly preferred acid monomers are acrylicacid and methacrylic acid.

With regard to the amount of acid monomer which is desirable orpreferred in the copolymer as discussed herein, it appears that there isa trade-off in terms of the acid strength of the monomer as indicated bypKa in aqueous solution and the amount of the acid monomer desirablyincluded in the copolymer. While a higher acid content can be toleratedand may be desirable for relatively weak acid monomers, for those acidmonomers that are relatively stronger acid monomers, the acid content ofthe copolymer is desirably less.

While a wide range of monomeric compositions are useful for thecopolymeric component of the fast hardening aqueous coating compositionemployed in the method of the present disclosure, in some embodiment itis preferred that the content of alpha, beta-ethylenically unsaturatedaliphatic carboxylic acid monomers in the copolymer is no more thanabout 5 weight percent, desirably up to about 4 weight percent, moredesirably up to about 3 weight percent, preferably up to about 2 weightpercent, and more preferably up to about 1 weight percent.

When present, the content of alpha, beta-ethylenically unsaturatedaliphatic carboxylic acid monomers in the copolymer is desirably atleast about 0.2 weight percent, more desirably at least about 0.3 weightpercent, preferably at least about 0.4 weight percent, and morepreferably at least about 0.5 weight percent.

In various embodiments, the content of alpha, beta-ethylenicallyunsaturated aliphatic carboxylic acid monomers in the copolymer isdesirably in the range from 0 to about 4 weight percent, more preferablyfrom about 0.2 to about 3 weight percent, still more preferably fromabout 0.3 to about 2 weight percent, and still more preferably fromabout 0.4 to about 1 weight percent, where the weight percentages arebased on the total weight of monomers in the polymerization mixture. Insome embodiments, the copolymer contains either no alpha,beta-ethylenically unsaturated aliphatic carboxylic acid monomers or isvery low therein, generally in the range from 0 to about 0.5 weightpercent.

In some embodiments, the copolymeric component of the fast hardeningaqueous coating composition is non-carboxylated. In such embodiments,the copolymer can consist essentially of (meth)acrylate monomers.

Within the scope of embodiments of the present disclosure are otherembodiments wherein the copolymer utilized would not be classified as a(meth)acrylate copolymer. Other copolymer types which can be utilizedinclude, for example, combinations of vinyl aromatic monomers with(meth)acrylate monomers, such as, for example, the styrene acrylates,and of vinyl aromatic monomers with conjugated diene monomers, such as,for example; styrene butadiene copolymers. These copolymers may benon-carboxylated or carboxylated.

In various embodiments, the composition employed can comprise ananionically stabilized aqueous dispersion of a copolymer comprising inpolymerized form a polymerization mixture, wherein the monomers of thepolymerization mixture include from about 1 to about 100 weight percentof one or more (meth)acrylate monomers, from about 0.1 to about 4 weightpercent of one or more (meth)acrylic acid monomers, from about 1 toabout 100 weight percent of one or more ethylenically unsaturatedmonomers which are not (meth)acrylate monomers or alpha,beta-ethylenically unsaturated aliphatic carboxylic acid monomers, fromabout 0.1 to about 4 weight percent of one or more alpha,beta-ethylenically unsaturated aliphatic carboxylic acid monomers whichare not (meth)acrylic acid monomers, or a mixture thereof.

A polymer with a preferred Tg for use in the present disclosure can beobtained from the polymerization of the monomers of a polymerizationmixture wherein the polymerized mixture, based on 100 parts by dryweight of the monomers polymerized, includes from about 30 to about 60percent of a soft monomer, such as, for example, butyl acrylate,ethylhexyl acrylate, butadiene, or a mixture thereof, and from about 40to about 70 percent of a hard monomer, such as, for example, methylmethacrylate, styrene, or a mixture thereof. Desirably, a soft monomerwhose homopolymer has a Tg of less than about −20° C. is copolymerizedwith a hard monomer whose homopolymer has a Tg of greater than about 80°C.

The copolymer can be made, for example, by charging the monomericingredients, water, and a surfactant (when employed) into a reactionvessel, purging the reaction vessel with an inert gas, such as, forexample, nitrogen, to remove essentially all the oxygen from the reactorvessel, and heating the reactor vessel to the reaction temperature,usually from about 80° C. to about 100° C. When the reactor vesselreaches the desired reaction temperature, an initiator is added to thereaction vessel, and the reaction is continued for about 2 to about 4hours. After the reaction is completed, the reactor vessel is cooled.This synthesis can yield an aqueous copolymeric composition comprisingthe copolymer in water. In some instances, the composition has theappearance of a milky liquid, while in other instances it looks like aclear solution.

The process of production of the copolymer may include the use of aseed, which may be a (meth)acrylate, polystyrene, or other seeds usefulto control the ultimate particle size of the copolymer produced, orotherwise useful in the production thereof. As is well known in the art,the regulation of initial seed can be used to control the ultimate rangeof particle sizes of the copolymer produced. Useful copolymer particlesizes are in the range of from about 700 to 10,000 angstroms.

Anionic, nonionic, and amphoteric surface active compounds, that is,surfactants, can be employed in the copolymer synthesis process.However, in some instances, no surfactant is required. Exemplaryanionic, nonionic, and amphoteric surfactants are SIPONATE A246L brandsurfactant available from Rhone-Poulenc, polyoxyethylene alkyl phenolsurfactants, and N,N-bis-carboxyethyl lauramine, respectively. Anotheruseful surfactant is DOWFAX 2EP, the sodium salt of dodecylatedsulfonated phenyl ether, which is available from The Dow ChemicalCompany, Midland, Mich. 48640, U.S.A.

A preferred class of surface active compounds are those in which thecation is derived from a volatile base, rather than a fixed base, suchas, for example, the ammonium salt of dodecylated sulfonated phenylether. In some embodiments, the fast hardening aqueous coatingcomposition can contain from 0 to no more than about 1 weight percent ofone or more surface active compounds, and preferably from about 0.1 toabout 0.5 weight percent of one or more surface active compounds.

Some initiators include thermally generated free radical sources such asperoxydisulfates, known in the industry as persulfates, perphosphates,and hydrogen peroxide. Generally, the initiator can be employed in aconcentration of about 0.1 to about 2 parts per hundred parts monomer byweight (phm), and preferably in a concentration of about 0.25 to about1.0 phm. A preferred class of initiators are those in which the cation,if present, is derived from a volatile base, such as, for example,ammonium peroxydisulfate.

As with the surfactants and initiators, in some emulsion polymerizationsystems it can be desirable to include various other emulsion polymerfolumation components. In some embodiments, the classes of thesecomponents will be those which do not increase the non-volatile saltload of the final composition. The term “non-volatile salt load” refersto those ionic components whose cation is not a volatile base-containingcation, such as, for example, sodium ion or potassium ion. Volatilebase-containing cations are preferred as constituents of ioniccomponents for use in the fast hardening aqueous coating compositionsemployed in the method of the present disclosure. In embodiments of thepresent disclosure, the non-volatile salt load of the fast hardeningaqueous coating composition can be no more than 2 weight percent, nomore than 1.5 weight percent, and can be from 0 to no more than about 1weight percent.

Other components which may be useful in some compositions includedispersants, thickeners, defoamers, biocides, flame retardants,antioxidants, and UV stabilizers. In some embodiments, these componentsare essentially free of triazoles.

In some embodiments, the aqueous dispersion of the copolymer may also bemade, for example, by a delayed addition polymerization process. In someinstances, the delayed addition polymerization process can includeforming a monomer mixture containing about 20 to about 80 weight percentsoft monomer, about 20 to about 80 weight percent hard monomer, and 0 toabout 5 weight percent olefinic carboxylic acid monomer.

Water is added to a reactor and heated, for example, to about 70° C. toabout 90° C., while purging the reactor with an inert gas, such asnitrogen, to remove substantially all oxygen from the reactor. Acatalyst is then added to the reactor. In some embodiments, a locus forpolymerization, that is, a surfactant and/or a surfactant containingseed can be added to the reactor before, simultaneously with, or afterthe catalyst addition to form a reactor charge. After the addition ofthe catalyst and locus for polymerization, the delayed addition of themonomer mixture is then commenced. The ensuing reaction forms theaqueous dispersion of the present disclosure. The addition of themonomer mixture typically takes up to about 4 hours. During the delayedaddition of the monomer mixture, additional catalyst is typically alsoadded to the reactor.

In an alternative synthesis procedure, a portion, for example up toabout one half of the monomer mixture, can be added to the reactor atthe beginning of the reaction along with the addition of the initialcatalyst and/or seed and/or surfactant.

After finishing the monomer mixture addition, further catalyst can beadded while maintaining the emulsion at the elevated reactiontemperature to ensure that substantially all of the monomers polymerize.The same catalyst can be used whenever one is employed. Exemplarycatalysts include, but are not limited to, t-butyl hydroperoxide,ammonium persulfate, hydrogen peroxide, and mixtures thereof.

In order to stabilize the emulsion, typically toward the end of themonomer mixture addition, the pH of the emulsion can be adjusted to avalue greater than about 7. Adjusting the pH to within the range of fromabout pH 7 to about pH 11 substantially neutralizes all olefiniccarboxylic acid groups on the polymer.

The pH of the emulsion may be adjusted from about 30 minutes before toabout 30 minutes after terminating the addition of the monomer mixture.In some embodiments, the pH adjustment occurs within about 15 minutesafter terminating the monomer mixture addition. Alternatively, theaqueous dispersion may be allowed to cool to ambient or room temperatureafter all the monomer mixture and catalyst have been added. Then, the pHof the cooled aqueous dispersion is adjusted. A volatile base can beemployed in each instance where the pH of the aqueous dispersion isadjusted.

The term “volatile base” as used herein is meant to include an organicor inorganic compound which is a weak or strong base. Also, the volatilebase has a sufficiently high vapor pressure and tendency to evaporate orotherwise volatilize out of the composition employed in the method ofthe present disclosure so that a pigment-containing formulation preparedfrom the composition has a no pick up time according to ASTM D711 of 20minutes or less. Alternatively, in the case of a pigment-free fasthardening aqueous coating composition, the volatile base has asufficiently high vapor pressure and tendency to evaporate or otherwisevolatize out of the composition employed in the method of the presentdisclosure so that a cast film of the composition has a hardening ratemeasurement rating of at least 5 within 20 minutes, measured accordingto the hardening rate measurement rating test described herein.

In some embodiments, the volatile base component of the composition canaccomplish the pH adjustment. For example, adding an amount of volatilebase that is at least about 0.2 weight percent based on 100 weight partssolids of the copolymer of the finished fast hardening aqueous coatingcomposition can be used to adjust the pH. In various embodiments, theamount of volatile base added can be at least about 0.3 weight percent,in some cases, the amount can be at least about 0.5 weight percent.Advantageously, no more than about 5 weight percent of a volatile base,based on 100 weight parts dry solids of the copolymer (a), can be added.It is preferable that the amount of volatile base be about 3 weightpercent or less, more preferably 2 weight percent or less, and even morepreferably 1.5 weight percent or less. In some embodiments, the finishedcomposition can contain an amount of volatile base that is from about0.2 to about 5 weight percent of the finished composition, based on 100weight parts solids of the copolymer. In addition, in variousembodiments, the amount of base can be about 0.2 to about 3 weightpercent of the finished composition, based on 100 weight parts solids ofthe copolymer of the anionically stabilized aqueous dispersion,preferably from about 0.2 to about 2 weight percent, and more preferably0.3 to about 1.5 weight percent.

Exemplary volatile bases are selected from the group consisting of aminecontaining bases, hydroxide-containing bases, and mixtures thereof.Dimethylamine, diethylamine, aminopropanol, ammonium hydroxide, and2-amino-2-methyl-1-propanol are typical bases, with the more volatilebases being more desirable, and ammonium hydroxide being preferred. In apreferred embodiment, the composition comprises from about 0.3 to about2.0 weight percent of a volatile base, based on 100 weight parts solidsof the copolymer.

In some embodiments, it can be desirable to have a minimal volatile basecontent. In such embodiments, a limited amount of a fixed based may beused in the composition, generally from about 0.1 to about 1.0 weightpercent, based on 100 weight parts of dry copolymer solids of component(a) of the composition, and preferably from about 0.1 to about 0.7weight percent, based on 100 weight parts of dry copolymer solids. Thismay be accomplished through the addition of a fixed base in thepolymerization process or the neutralization process, or as a result ofthe use of some polymerization component in salt form in which thecation is not volatile, such as, for example, the sodium salt of ananionic surfactant, followed after polymerization by pH adjustment witha volatile base. Desirable fixed bases for use in the present disclosureinclude sodium and potassium hydroxides, sodium hydroxide beingpreferred.

In embodiments where a fixed base is used in the composition, the amountof the volatile base can be considerably reduced from what it would beotherwise, for example, to about 2 weight percent or less, preferably toabout 1.5 weight percent or less, and more preferably to about 1 weightpercent or less.

In some cases the relatively strong odor of ammonia associated with acomposition containing a relatively high concentration of ammonia may beundesirable. In this circumstance, it may be possible to reduce theammonia content by using a volatile base component that is a mixture ofvolatile bases, such as, for example, a mixture of ammonium hydroxide(ammonia) and a less volatile organic base, such as, for example,aminomethylpropanol.

In some embodiments, the organic base of the mixed volatile base can beat least about 0.25 weight percent, desirably up to about 0.5 weightpercent, but most likely not more than about 1 weight percent. As withthe addition of small amounts of fixed base containing compositions,those with a mixed volatile base can use a lesser amount of ammoniumhydroxide than if it were the sole base, typically, about 2 weightpercent, based on 100 weight parts of dry copolymer solids of thecomposition, or less, preferably about 1.5 weight percent or less, andmore preferably about 1 weight percent or less.

The addition of the volatile base component as described above resultsin an increase in the pH of the composition sufficient that the pH ofthe finished fast hardening aqueous coating composition has a pH that isat least about pH 8, desirably at least about pH 9, preferably at leastabout pH 9.5, and more preferably at least about pH 9.8. It is notnecessary, and generally is not desirable, for the pH of the compositionto be greater than about pH 12, and, advantageously pH of thecomposition is about pH 11 or less, preferably, the pH of thecomposition is about pH 10.8 or less, more preferably, about pH 10.5 orless. Thus, the desirable pH range for the finished aqueous coatingcompositions, including the fast hardening aqueous coating compositions,is from about pH 8 to about pH 12, more desirably from about pH 9.5 toabout pH 10.8 or pH 11, and preferably from about pH 9.8 to about pH10.5.

The polymerization process yields a preferred embodiment of the aqueousdispersion of the present disclosure. pH adjustment at the end of theprocess provides the second of the elements of the fast hardeningaqueous coating composition, which is then ready for the addition of athird component, which preferably is a polyimine and/or polyamine. Thesolids content of the aqueous dispersion is generally at least about 40weight percent, based on total aqueous dispersion, preferably in therange of about 45 to about 70 weight percent, and more preferably in therange of from about 45 to about 60 weight percent. These numbers are notgreatly affected by the addition of the polyimine and/or polyamine,since it can be added as an aqueous solution, about 50 weight percent ofwhich is the polyimine and/or the polyamine.

Suitable latexes can be produced using conventional emulsionpolymerization techniques. Thus, for example, the monomers to beemployed in the particular latex involved are typically dispersed withagitation sufficient to emulsify the mixture in an aqueous medium, whichmay contain known emulsifying agents such as surfactants as well asother ingredients conventionally employed in the art as polymerizationaids, including conventional chain transfer agents. Such monomers canthen be subjected to polymerization with the aid of a conventionalsource for generating free radicals, including conventional free radicalpolymerization catalysts, activating radiation, or other means.

Free radical polymerization catalysts suitable for use in the foregoingpolymerizations include those already known to promote emulsionpolymerization. Among such catalysts are oxidizing agents such asorganic peroxides such as t-butyl hydroperoxide and cumene hydroperoxideinorganic oxidizing agents such as hydrogen peroxide, potassiumpersulfate, sodium persulfate, ammonium persulfate, and catalysts which,like redox catalysts, are activated in the water phase, for example, bya water-soluble reducing agent.

Such catalysts are employed in an amount sufficient to causepolymerization, that is, in a catalytic amount. As a general rule, anamount ranging from about 0.01 to about 5 weight percent based upon thetotal monomer to be polymerized is sufficient. Alternatively, other freeradical producing means, such as exposure to activating radiations, canbe employed rather than heat and/or catalytic compounds to activate thepolymerization.

Suitable emulsifying agents which can be employed include the anionicand nonionic emulsifiers customarily used in emulsion polymerization.Usually at least one anionic emulsifier is included while one or morenonionic emulsifiers can also be present. Representative types ofanionic emulsifiers are the alkyl aryl sulfonates, alkali, metal alkylsulfates, the sulfonate alkyl esters, the fatty acid soaps, and thelike. Specific examples of these well-known emulsifiers includedodecylbenzene sodium sulfonate, sodium butylnaphthalene sulfonate,sodium lauryl sulfate, disodium dodecyl diphenyl ether disulfonate,N-octadecyl disodium sulfosuccinate, dioctyl sodium sulfosuccinate, and,preferably, the corresponding ammonium salt forms. Such emulsifyingagents can be employed in varying amounts so long as adequateemulsification is achieved to provide dispersed polymer particles havingthe desired particle size and particle size distribution. However, as ageneral rule, an amount ranging from about 0.01 to about 5 weightpercent, based upon the total monomer to be polymerized isadvantageously employed.

Conventional chain transfer agents can also be employed in theproduction of latexes and, indeed, in polymerization stages employing analiphatic conjugated diene, it is preferable to do so. Examples of suchlong chain mercaptans are, for example, lauryl mercaptan, dodecylmercaptan, and other known chain transfer agents.

Other ingredients known in the art to be useful for various specificpurposes in emulsion polymerization can also be employed in theaforementioned latexes. For example, when the polymerizable constituentsfor a given latex include a monoethylenically unsaturated carboxylicacid monomer, polymerization under acidic conditions is preferred. Asused herein, polymerization under acidic conditions includes conditionswhere the aqueous media has a pH value of from about pH 2 to pH 7,especially from about pH 2 to about pH 5. In such instances, the aqueousmedium can include acids and/or salts to provide the desired pH valueand possibly a buffered system.

The latexes can be prepared by conventional emulsion polymerizationtechniques. For example, in some embodiments, water and a seed latex ora micelle-forming surfactant are introduced into a reactor equipped withpumps to deliver monomer and aqueous feeds. The reactor can be purgedwith nitrogen and heated. Over a period of several hours, the monomerstreams are added as well as a stream containing water, aqueoussurfactant, and polymerization initiator. Following the addition of themonomer streams and the aqueous streams, the reaction mixture can bemaintained at the reaction temperature for additional reaction time toensure extensive reaction before cooling. The latex then may be steamdistilled to reduce the concentration of unreacted monomers.

Numerous other copolymers and copolymer-containing latexes can beutilized in the composition employed in the method of the presentdisclosure, for example, as disclosed in U.S. Pat. Nos. 6,075,079;5,201,948; 5,213,901; 5,198,492; 5,185,396; 5,182,327; 5,173,534;5,212,251; 5,059,456; 4,293,476; 4,666,777; 4,658,003; 4,742,108;4,644,032; 4,623,678; 4,087,572; 4,012,355; 5,236,991; 5,157,084;5,045,576; 4,973,670; 4,972,018; 4,968,740; 4,962,154; 4,863,979;4,857,631; 4,806,207; 4,508,869; 4,733,005; and 4,707,221.

While the compositions employed in the method of the present disclosurecomprise a copolymer, and for some compositions a single copolymer isused, it is within the scope of the present disclosure to employ blendsof copolymers along with the other elements of the composition. Apreferred embodiment comprises a single copolymer along with the otherelements of the composition.

When a blend of copolymers is employed rather than a single copolymer,it is desirable for one or more of the copolymers of the blend to becapable of film formation at ambient temperatures while one or moreother copolymers of the blend may be harder, that is, the Tg's of thenon-film forming copolymers may be greater than about 40° C. For thiscomponent of the blend, it is possible for the Tg to be up to 50° C., tobe up to 60° C., to be up to 70° C., to be up to 80° C., to be up to 90°C., to be up to 100° C., or even to be up to 130° C.

Polyimines are polymers produced by the polymerization of imine monomersthat do not contain carbon-carbon ethylenic unsaturation, but, rather,contain either carbon-nitrogen unsaturation or exist as heterocyclicring compounds. As a result, polyimines have nitrogen atoms in thepolymer backbone. Depending upon the pH of the system, these nitrogenatoms in the backbone of the polymer may be protonated, just as wouldthe nitrogen atom of an amine group attached to a polymer. However,because of the placement of the nitrogen atom in the polymer backbone,there are significant differences from pendant amine chemistry.

The polyimine can be employed in an amount sufficient to result in afast hardening aqueous coating composition. In some embodiments, theamount of polyimine employed is from about 0.2 to about 5 weight parts,based on 100 weight parts of component (a) solids. In variousembodiments, the amount of polyimine employed can be from about 0.3 to 3parts, and more preferably is from about 0.5 to about 2 parts.

Suitable polyimines for use in the fast hardening aqueous coatingcomposition employed in the method of the present disclosure include,for example, polyethylenimines and polypropylenimines, desirably with amolecular weight of at least about 250, preferably with a molecularweight of at least about 400, and more preferably with a molecularweight of at least about 700. When lower molecular weight polyimines areused as constituents of the fast hardening aqueous coating composition,the rate of hardening is reduced.

The molecular weight of the polyimine should be no greater than about20,000, desirably, no greater than about 10,000, more desirably nogreater than about 5,000, preferably no greater than 3000, and morepreferably no greater than about 2000. When higher molecular weightpolyimines are used as constituents of the fast hardening aqueouscoating composition, the viscosity of the composition is increased andthe compositions are more difficult to use.

Preferred ranges for the molecular weight of the polyimine component ofthe composition are from about 250 to about 20,000, desirably from about400 to about 10,000, more desirably from about 400 to about 3000, andpreferably from about 700 to about 2000.

Preferred polyimines for use in the composition include polyethylenimine(PEI) that has an average molecular weight of about 2000. The materialis available from BASF as LUPASOL G-35, CAS No. 9002-98-6. Othercommercially available PEI's include LUPASOL FG with an averagemolecular weight of about 800, and LUPASOL G-20 with a molecular weightof about 1300. The molecular weights of the PEI's have been determinedby light scattering techniques.

Polyamines are polymers produced by the polymerization of amine monomersby hydrolysis of polymers to amine functionality. In some embodiments, apolyamine is employed in an effective amount sufficient to result in afast hardening aqueous coating composition used in methods of thepresent disclosure. In other words, the fast hardening aqueous coatingcomposition used in methods of the present disclosure can include anamine-containing latex.

As used herein, “amine-containing” latex refers to a latex havingpendant amine functional groups. The amine-containing latexes may beprepared in accordance with any of a number of methods, including, butnot limited to: addition polymerization of ethylenically unsaturatedmonomers containing amine-functionality; polymerization of monomerswhich readily generate amines by hydrolysis; reactions of aziridineswith carboxyl-containing polymers; reactions of polymers containing anenolic carbonyl group (e.g., acetoacetoxyethy methacrylate (AAEM), anddiamines); reactions of amines with epoxy-containing polymers; andreactions of amine with polymers of vinyl benzyl chloride. Suchpolymerization reactions are known in the art, and examples ofpreparation of these and other suitable amine-containing latexes may befound in the following publications: U.S. Pat. No. 3,847,857 (Chou etal.); U.S. Pat. No. 4,119,600 (Bakule et al.); U.S. Pat. No. 5,364,891(Pears et al.); U.S. Pat. No. 5,494,961 (Lavoie et al.); and U.S. Pat.No. 4,367,298.

The fast hardening aqueous coating composition employed in the method ofthe present disclosure can be prepared by mixing the polyimine and/orpolyamine with the anionically stabilized aqueous dispersion to whichthe volatile base has been added, as discussed herein. This can beaccomplished in a number of ways, however, addition of the polyimineand/or the polyamine as an aqueous solution, e.g., about 50 weightpercent polyimine, is advantageous. The triazole can be added at anumber of times during the preparation of the composition. In oneembodiment, the triazole is added to the other components of thecomposition during the preparation of a paint, e.g. a traffic paint,that will contain the composition.

If desired, one or more additives may be incorporated into the coatingcompositions in order to modify the properties thereof. Examples ofthese additives include thickeners, dispersants, pigments, dyes and/orcolorants, biocides, anti-foaming agents, optical brighteners, wetstrength agents, lubricants, water retention agents, crosslinkingagents, surfactants, buffering agents, and the like. In someembodiments, the composition is in the form of a paint, and can beformulated according to methods well known to those skilled in the art.Due to the surprisingly good plate out resistance properties imparted bythe triazole, the composition can be advantageously employed infast-hardening traffic paint formulations.

Advantageously for the present disclosure there is a Reduction InPlating of at least 10%, preferably at least about 25%, more preferablyat least about 50%, and even more preferably at least about 75%. As usedherein, the term “Reduction in Plating” refers to the degree of plateout reduction as calculated herein.

As mentioned herein, the method of the present disclosure can beemployed in applications where plate out onto metal-containing surfaceshas been a problem. Examples of some of the more commonly used metalsfor industrial equipment, including, for example, tanks and plumbing,are stainless steel, carbon steel, copper, and aluminum. These and othertypes of metals often come in contact with latex or latex containingformulations during production, processing, storage, or application.Steels are designated by grade, type, and class. Grade is used to denotechemical composition; type is used to indicate deoxidation practice; andclass is used to describe some other attribute such as strength level orsurface smoothness. ASTM or ASME are the most widely used specificationsfor steel products in the United States; however, the grade, type, andclass terms are used somewhat interchangeably. Stainless steel is knownfor its outstanding corrosion resistance and is primarily an alloy ofiron, chrome, and nickel with very low carbon content. 18-8 is a genericdesignation that is used to indicate stainless steels such as 302, 303,304, 305, 384 having compositions containing approximately 18% chromeand 8% nickel. 316 stainless steel is often the metal of choice foraqueous contact and is composed of 67.9% Fe, 17% Cr, 12% Ni, 3.0% Mo,and only 0.10% C by weight. Carbon steels have lower corrosionresistance than stainless with carbon contents in the range of about0.3-1.1%. They also contain less than 1.65% Mn, 0.60% Si, and 0.60% Cuwhile alloy steels have greater levels of those three elements.Contrasted to these are wrought iron which contains 98.5% Fe with 1.5%C, and cast iron with 97% Fe with 3% carbon.

Almost all carbon steel that is exposed to the external environment iseither zinc plated or hot dip galvanized (also a zinc coating). Commongrades of carbon steel that are zinc plated are Steel Grade 2 (lowcarbon steel), Steel Grade 5 (medium carbon steel), and Steel Grade 8(medium carbon alloy steel). Because galvanized steel has a much thickercoating than zinc plated steel, galvanized steel is also more corrosionresistant.

Other metals that are occasionally used in exterior and some internalindustrial applications include brass, bronze, silicon bronze, andaluminum. Brass and bronze are alloys of copper, but they also containsome zinc. A typical yellow brass composition is 67% Cu and 33% Zn,while naval brass is 60% Cu, 39% Zn, and 1% Sn. Bronze is often used inmarine applications and has greater strength and more corrosionresistance than brass. A typical salt water bronze composition is 45%Cu, 33% Ni, 16% Sn, and 5.5% Zn.

Specific Embodiments

The following examples are given to illustrate embodiments of thepresent disclosure and should not be construed as limiting in scope. Allparts and percentages are by weight unless otherwise indicated.

Test Methods

pH

pH is measured on latexes and paints at room temperature using a ColeParmer pH 100 Series pH meter with autotemperature compensation.

Brookfield Viscosity

This viscosity was measured on latexes and paints using a BrookfieldDV-II+ digital viscometer (available from Brookfield EngineeringLaboratories, Inc., Stoughton, Mass., USA). Viscosity determinations aremade in either 20 ml scintillation vials or in ½ pint (about 236milliliters) lined cans. The measurements are made at room temperatureat an instrument speed of 30 rotations per minute (rpm) using theappropriate spindle providing torque readings between 10-100%.

Paint Consistency

This viscosity is measured according to ASTM D562 using a digitalBrookfield Model KU-1 viscometer available from Brookfield Engineering.This instrument uses the same paddle spindle and rotation speed of aStormer viscometer, and the viscosity readout is also in Krebs Units(KU). All measurements are made at 25° C. in a½ pint can.

No-Pick-Up

This dry time measurement is run using ASTM D711. Draw-downs of thelatex or paint are made on glass using a 10 mil gap film applicator. Inthis test, a timer is started, and a no-track wheel is rolled over thecoating repeatedly at 1 minute (min) intervals until the coating doesnot stick to the wheel. The number of minutes elapsed is recorded as theNo-Pick-Up dry time.

Dry-to-Touch

This dry time measurement is conducted by making drawdowns of the latexor paint using a 3 mil gap film applicator on a sealed black Lenetachart. A timer is immediately started, and the dry time is determined byperiodically touching a finger to the coating at 15 second (sec)intervals until there is no transfer of liquid and the surface istack-free. The elapsed time is recorded as the 3 mil Dry-to-Touch time.

Latex Heat-Age Stability

This test is conducted by placing 2 milliliters (ml) of latex into a 3ml vial with cap. The capped latex is then placed into an oven at 80° C.At one day intervals, the vial is removed, cooled to room temperature,and examined by rocking back and forth to determine if the contents arestill fluid. The number of days to solidification is recorded as theLatex Heat Age Stability. The test is stopped at 14 days.

Paint Heat Age Stability—Method A

This test is conducted by placing 18 ml of latex paint into a 20 mlscintillation vial with cap. The vial with latex is placed into a 50° C.convection oven and removed at 24 hr intervals for examination. At eachtime interval, the sample is allowed to cool to room temperature, andthen a Brookfield DV-II+ viscosity measurement is made using Spindle #4at 30 rpm. The viscosity is plotted over time to provide a relativeindication of the heat-age stability. If gellation of the sample occurs,the time to gellation is also recorded.

Paint Heat Age Stability—Method B

This method is conducted with the paint in ½ pint cans, leaving about0.5 inches (0.5″) (1.27 centimeters (cm)) of free space at the top. Thesealed paint can is placed in a oven at 50° C. and removed daily forexamination. If the latex is gelled, the elapsed time in days isrecorded as the Heat-Age-Stability. The cans are tested in this mannerfor up to 14 days.

Hardening Rate Measurement

The term “fast hardening aqueous coating composition” as used herein isdefined as a composition wherein a cast film of the composition has ahardening rate measurement rating of at least 5 within 20 minutes aftercasting, measured at a temperature of 25° C. and relative humidity of 50percent.

A film of the composition to be tested is cast on a glass surface with a0.51 mm (20 mil) draw down bar. The hardening rate for the compositionis then determined by finger testing of the drying films under ambientconditions of temperature of 25° C. and relative humidity of 50 percent.This test must be performed in still air. The composition is rated every10 minutes on a rating scale of 1 to 8 as follows:

1. Wet composition, flows easily.

2. Skin over wet composition, skin is sticky.

3. Thick paste, composition does not flow.

4. Composition is slightly hard, very thick paste.

5. Composition is not sticky or wet, but is receptive to fingerprintwith soft pressure, soft when twisted or gouged.

6. Composition is receptive to fingerprint only with firm pressure.

7. Composition is hard, is not receptive to fingerprint, iscloudy/white.

8. Composition is hard and clear.

Plate Out Test

A gravimetric method is used for determining the amount of latex platingthat occurs when latex or a latex-containing composition is in contactwith a metal surface. The test apparatus consists of a closed cellcontaining a weighed quantity of latex or paint. A weighed metal sampleis then partially immersed in the latex in the closed cell for a setperiod of time. On removing the metal sample, the loss of wet latex orpaint in the cell (Wet Plating) and the amount of dry latex or paintplating on the metal substrate (Dry Plating) are gravimetricallydetermined. The ratio of those two weights yields the average PlatingSolids.

Commercial bolts or lag screws are used for the test metal substrates.They are a preferred test metal substrate because they have a largesurface area per unit volume, are uniform in size and geometry, are easyto obtain, are low cost, require no preparation, have a threadedgeometry that retains the plating, have geometry and size that allowsmall volumes of sample liquid for the test, and are available in avariety of metal types in a given geometry. Common threaded bolts andlag screws of 2″ (5.08 cm) length and ¼″ (0.635 cm) diameter are thestandard test geometry. Full thread hex head tap bolts of zinc platedsteel, hot dip galvanized steel, and solid bronze construction are usedfor most metal stability testing. As brass is not commonly available ina hex head configuration, full thread solid brass machine screws withslotted pan or flat heads are employed. The shaft of the brass machinescrew is identical to the hex head bolts of the same diameter. The 2″tap bolts and machine screws have standard threads of 20 threads/in for¼ diameter. The common designation for this geometry is ¼20×2. Hex headlag bolts (often referred to as lag screws) of zinc steel and galvanizedsteel construction are also used for metal testing, and these are apreferred geometry for these metals. The 2″ hex head lag screws of ¼″diameter have threads that are wider (10 threads/inch) and deeper thantap bolts. Unlike bolts which have a relatively flat end, lag screwshave a pointed end and are designed for anchoring into wood substrates.

The test cells for containing the test metals are glass 20 ml disposablescintillation vials with plastic caps. These cells are employed becausethey are large enough to contain the 2″ test metals when capped, easy toseal, transparent, low in cost, inert, and readily available. Thedimensions of these scintillation vials are 60 mm in height and 24 mm IDwith a neck opening of 16 mm. Although these vials hold 20 ml when full,only 15 ml of liquid sample is used for each test for partial immersionof the bolts to a depth of 32 mm. With 15 ml of liquid sample in thescintillation vial, the immersion depth of a ¼ in (˜6 mm) diameter boltor screw is 32 mm. The bolt extends about 28 mm above the surface of theliquid with the head of the bolt or screw at the top residing justinside the vial neck for positioning and ease of removal.

The following is a detailed procedure for this method. All weighings arewith an analytical balance to four decimal places.

1) Number and weigh (W_(M1)) a series of bolts or lag screws. The testmetals are all from the same supplier and same lot for a given testseries.

2) Inject 15.0 ml of sample liquid into each vial by syringe, and thencap the vial.

3) Weigh (W_(VL1)) each capped vial containing the 15 ml of latex orlatex paint.

4) Place a matching numbered bolt or lag screw into each vial containingthe latex or paint with the head up and the threaded end down. Recap thevial.

5) Allow the samples to sit undisturbed for the specified immersiontime. The standard period is 24 hr.

6) At the end of the immersion period, carefully remove each bolt or lagscrew with tweezers avoiding contact of the plated material with theneck or sides of the vial. Let any free latex drip back into the vial(usually only 1-3 drops), and then place the head of each bolt into anotched metal rack for drying. Recap the vial.

7) Weigh (W_(VL2)) each capped vial containing the remaining unplatedlatex or paint to determine the “Wet Plating” (P_(W)), where(P_(W))=W_(VL1)W_(VL2).

8) After air drying the plated bolts for 1 hr., place the metal rackcontaining the bolts into an air circulating oven at 120° C. for 2 hr.Remove the metal rack from the oven, and allow the samples to cool toroom temperature (˜15 min).

9) Weigh (W_(M2)) each plated bolt and then calculate “Dry Plating”(P_(D)), where P_(D)=W_(M2)−W_(M1).

Dividing the Dry Plating (P_(D)) by the Wet Plating (P_(E)) gives theaverage “Plating solids” (P_(S)), where P_(S)=P_(D)/P_(W)*100%.

For plated paint samples, the bolts or screws are gently rinsed withdeionized water immediately after removal from the vials. In thisprocedure, the bolt is removed from the cell with tweezers and thenimmersed in a container of deionized water. The bolt is gently swirledin the container three times and then removed and placed in a dryingrack. This procedure removes any free paint that is not really plated.Latex or paint that is truly plated on metal becomes water insoluble andremains on the threads during rinsing. With mostly inert test metalssuch as high grades of stainless steel, it is typical to see very littleor no latex or paint on the threads when the metal is removed from thevial. Gentle rinsing will typically remove latex that is not trulyplated. Accordingly, the test is more meaningful when a plate outsusceptible metal, such as zinc plated steel, is used for plate outtesting.

Plating Reduction

Embodiments of the present disclosure advantageously result in areduction in plating on metals. When a composition is compared forplating with and without triazole, the “Plating Reduction” (PR) iscalculated using the following formula for dry plating:% PR=(P _(DC) −P _(DT))/P _(DC)×100

where P_(DC) is dry plating of the “control” composition (withouttriazole) and P_(DT) is the dry plating for the composition withtriazole.

Materials

The following materials are used in the examples.

Latexes: UCAR™ Latex DT211, UCAR™ Latex DT250, UCAR™ Latex DT400 (TheDow Chemical Company), FASTRACK 2706, 3427, and HD-21A (Rohm and HaasCompany).

Triazoles: benzotriazole (ReagentPlus, 99%, Aldrich), 40% aqueous sodiumbenzotriazol, Wintrol B 40NA (Wincom Inc.), 50% aqueous sodiumtolyltriazole, Wintrol T 50NA (Wincom Inc.), and ammonium benzotriazole.The ammonium benzotriazole is prepared by reacting the ReagentPlusbenzotriazole with an excess of aqueous ammonia; it has a pH of 9.9 andis an aqueous solution having 25% solids.

Biocide: DOWICIL 75 (The Dow Chemical Company); Defoamer: DREW L-493(Drew Chemical, Division of Ashland Chemical); Propylene Glycol (The DowChemical Company); Titanium Dioxide: TiPure R901 (DuPont); Dispersant:RHODIA 226/35 (Rhodia); Calcium Carbonate: OMYACARB 5 (OmyaCorporation); Thickener: NATROSOL 250 HBR (Aqualon, Division ofHercules); Coalescing Aid: TEXANOL (Eastman Chemical).

Test Paint Formula:

Solids Charge Raw Material (%) (g) Latex Binder  50.5  515.3 Dowcil 75100.0   0.6 Drew L-493 100.0   2.2 Rhodia 226/35  35.0   8.5 PropyleneGlycol  0.0  22.4 1% Natrosol 250HBR  1.0  33.6 Ti-Pure R-900 100.0 112.0 Mix on disperser for 3 minutes Omyacarb 5 100.0  890.5 Mix ondisperser for 4 minutes Texanol  0.0  23.5 Drew L-493 100.0   3.4 TotalCharge 1612.0

The following Examples are illustrative of the process for incorporationof triazole and for testing of plating on metals using the Plate OutTest:

EXAMPLE 1 Addition of Sodium Tolyltriazole to Latex and Testing forPlating on Zinc Plated Steel

Into a 600 ml beaker is charged 400.0 g of 50% solids UCAR Latex DT250with gentle mixing on a lab stirrer. 8.00 g of Wintrol T 50NA is addedby syringe to the latex with stirring. The concentration of sodiumtolyltriazole is 1.0% active based on latex solids (ABOLS). Theprocedure is repeated using other triazole concentrations, as shown inTable 1.

A 3 mil wet drawdown of the latex with NaTTA is homogeneous and free ofgrit particles, similar to the same latex without NaTTA. 15 ml samplesof the latex with and without NaTTA are evaluated using the Plate OutTest with zinc plated steel lag screws. After 24 hr, the lag screws areremoved and compared gravimetrically for latex plating on the metal bydrying the plated screws in a convection oven at 120° C. for 2 hr. Theaverage dry plating on the screws without NaTTA is 1.004 g. The averagedry plating on the screws with NaTTA is 0.481 g, which is an 52%reduction in plating relative to the control latex without NaTTA.

EXAMPLES 2-5

The procedure of Example 1 is repeated with other combinations of metal,triazole, and latex. The results are summarized in Table 1.

EXAMPLE 6 Incorporation of Sodium Tolyltriazole into Latex Paint andTesting for Plating on Metal

A traffic paint is prepared by charging 350.0 g of the NaTTA latex ofExample 1 into a 1000 ml stainless steel beaker with low mixing on ahigh-speed lab disperser. The following components are subsequentlyadded with mixing: 0.4 g DOWICIL 75 biocide, 3.8 g DREW L-493 antifoam,5.8 g RHODIA 226/375 pigment dispersant, 15.2 g propylene glycol, 23.1 g1% NATROSOL 250HBR thickener solution, 76.1 g Ti-Pure R-900 titaniumdioxide, 604.9 g OMYACARB 5 calcium carbonate extender, and 16.0 gTEXANOL coalescing aid. The resulting paint is mixed for 5 min at highspeed to maintain a moderate vortex. When cooled to room temperature,the paint has a Stormer KU viscosity of 85KU and pH of 10.6. Anotherpaint is prepared in an identical fashion using the same lot of DT250latex without NaTTA added. 15 ml samples of the paint with and withoutNaTTA are evaluated using the Plate Out Test with zinc plated steel lagscrews. The dry plating on the screw without NaTTA is 5.21 g. The dryplating on the screw with NaTTA is 0.72 g. The reduction in plating withNaTTA relative to the control paint is 86.2%.

EXAMPLES 7-30

The procedure of Example 6 is repeated subject to various changes, whichare shown in Table 1 along with the results of testing. The results aresummarized in Table 1.

The data in Table 1 illustrates the dry plating (P_(D)) amounts obtainedat up to four triazole concentrations and the percent plating reduction(PR) obtained at 1.0% triazol “active based on latex solids” (ABOLS)concentration in the latex or latex paint. The variables in Table 1include variation in latex type, latex lots, latex paint type, latexpaint lot, type of metal, and type of triazole added whereBTA=benzotriazole, AmBTA=ammonium benzotriazole, NaBTA=sodiumbenzotriazole, NaTTA=sodium tolyltriazole, ZPS=zinc plated steel, andHDGS=hot dipped galvanized steel.

TABLE 1 Percent Plating Additive Concentration (% ABOLS) Reduction atExample 0 0.5 1 1.5 1.0% Additive Number Latex Metal Additive DryPlating (g) Concentration 1 DT250 ZPS NaTTA 1 — 0.48 — 52 2 DT250 ZPSBTA 0.71 0.3 0.17 0.12 76.1 3 DT250 Brass BTA 0.46 0.11 0.11 0.11 76.1 4DT211 HDGS NaTTA 0.29 0.09 0.1 0.05 65.5 5 DT250 HDGS NaTTA 0.29 0.090.03 — 89.7 6 DT250 ZPS NaTTA 5.21 — 0.72 — 86.2 7 DT250 Brass BTA 1.40.6 0.6 0.6 57.1 8 DT250 ZPS AmBTA 5.2 2.8 1.7 1.7 67.3 9 DT250 ZPSNaBTA 5.2 3 1.7 2 67.3 10 DT250 ZPS NaBTA 4.84 — 1.38 — 71.5 11 DT250ZPS NaBTA 4.2 1.9 0.7 0.7 83.3 12 DT250 ZPS NaBTA 4.7 — 1.7 — 63.8 13DT250 ZPS NaBTA 6.2 — 1.7 — 72.6 14 DT250 ZPS NaBTA 6.2 4 2.5 — 59.7 15DT250 ZPS NaTTA 6.2 3.9 2 — 67.7 16 DT250 Brass NaTTA 0.88 0.28 0.1 0.1188.6 17 DT250 Brass NaBTA 0.88 0.3 0.09 0.11 89.8 18 DT250 ZPS NaTTA 5.84.1 2.4 — 58.6 19 DT211 ZPS NaTTA 3.6 — 2.2 — 38.9 20 DT250 ZPS NaTTA5.4 — 3 — 44.4 21 DT211 Brass NaTTA 1.46 — 0.11 — 92.5 22 DT211 ZPSNaTTA 5.22 — 0.48 — 90.8 23 DT211 HDGS NaTTA 4.88 — 1.81 — 62.9 24 DT250Brass NaTTA 1.1 — 0.23 — 79.1 25 DT250 ZPS BTA 4.2 1.9 1 1.1 76.2 26DT250 HDGS NaTTA 4.22 — 1.67 — 60.4 27 DT250 ZPS NaTTA 4.2 — 2.8 — 33.328 DT250 ZPS NaTTA 4.9 — 1.3 — 73.5 29 DT250 ZPS NaTTA 4.9 — 1.8 — 63.330 DT250 ZPS NaTTA 4.67 — 1.42 — 69.6 *Not an embodiment of the presentdisclosure.

As can be seen from Table 1, the amount of dry plating on the metalsdecreases as triazole is added to the compositions. For example, inExample 30, the amount of dry plating on zinc plated steel is 4.67 gwith no triazole, and the amount of dry plating decreases to 1.42 g whenthe composition has a 1 percent triazole concentration.

EXAMPLES 31-41

In another investigation of paint plating on metals, commercial samplesof waterborne traffic paints are obtained from the Texas Department ofTransportation (TxDOT), Materials and Pavement Section, ConstructionMaterials Division, Austin, Tex. These are samples from commercialproduction batches of paint made by traffic paint producers and sent tothe Texas DOT lab for road striping qualification. In the table below,three different paint suppliers are represented with both white andyellow traffic paints, and the fast-dry latexes in those paints asspecified by TxDOT are either FASTRACK HD-21A or UCAR Latex DT400. Theamount of latex solids in each paint as specified by TxDOT is 16.1% byweight based on total wet paint. Each paint sample is divided into twocontainers. To one container, sodium tolyltriazole is added at aconcentration of 1.0% active based on latex solids (ABOLS) in the paint.The paints with and without sodium tolyltriazole are evaluated using thePlate Out Test, and the results are shown in Table 2.

TABLE 2 Dry Plating on ZPS (g) % Dry Paint Produc- Sup- Paint WithPlating Example Sup- tion Paint plied 1.0% NaTTA Reduc- Number plier LotColor Paint* (ABOLS) tion 31 Lab — Yellow 2.442 1.028 57.9 32 A 1 Yellow3.517 0.729 79.3 33 A 2 Yellow 3.578 0.674 81.2 34 A 3 White 4.349 0.66184.8 35 A 4 White 4.016 0.66 83.6 36 B 1 Yellow 0.582 0.082 86 37 B 2Yellow 0.41 0.045 89 38 B 3 White 0.877 0.074 91.6 39 B 4 White 1.0660.075 93 40 C 1 Yellow 0.426 0.213 49.9 41 C 2 White 0.731 0.154 78.9*Not an embodiment of the disclosure.

Similar to the results of Table 1, Table 2 shows that when triazole isadded to the paint, the dry plating on the zinc plated steel decreases.For example, in Example 38, the addition of 1% triazole causes theamount of dry plating to decrease from 0.877 g to 0.074 g for a 91.6percent reduction in dry plating.

What is claimed:
 1. A method of coating, the method comprising applyingas a coating a composition comprising a triazole selected from the groupconsisting of benzotriazole, salts of benzotriazole, tolyltriazole,salts of tolyltriazole and mixtures thereof as a plate out reducingagent, the composition further comprising: (a) an anionically stabilizedaqueous dispersion of a copolymer, the copolymer comprising inpolymerized form a polymerization mixture comprising two or moreethylenically unsaturated monomers where, based on the total weight ofall ethylenically unsaturated monomers in the polymerization mixture,from 0 to about 4 weight percent of the monomers are alpha,beta-ethylenically unsaturated aliphatic carboxylic acid monomers; (b)an effective amount of a polyimine or polyamine; and (c) an effectiveamount of a volatile base; where the amount of triazole is from about0.01 to about 5 weight parts, based on 100 weight parts solids of thecopolymer of (a).
 2. The method of claim 1, wherein the polyimine has amolecular weight of from about 250 to about 20,000.
 3. The method ofclaim 1, wherein the amount of triazole is from about 0.1 to about 3weight parts, based on 100 weight parts solids of the copolymer of (a).4. The method of claim 3, wherein the amount of triazole is from about0.25 to about 1.5 weight parts, based on 100 weight parts solids of thecopolymer of (a).
 5. The method of claim 1, wherein the triazolecomprises tolyltriazole.
 6. The method of claim 1, wherein the triazolecomprises benzotriazole.
 7. The method of claim 1, wherein the triazolecomprises at least one alkali metal salt of benzotriazole or alkalimetal salt of tolyltriazole.
 8. The method of claim 7, wherein thetriazole comprises sodium tolyltriazole.
 9. The method of claim 7,wherein the triazole comprises sodium benzotriazole.
 10. The method ofclaim 1, wherein the triazole comprises at least one ammonium salt ofbenzotriazole or ammonium salt of tolyltriazole.
 11. The method of claim1, wherein the effective amount of volatile base is sufficient to raisethe pH of the composition to a pH that is at least about 9.5.
 12. Amethod, comprising: incorporating into an aqueous latex an amount of atriazole selected from the group consisting of benzotrizole, salts ofbenzotriazole, tolyltriazole, salts of tolyltriazole and mixturesthereof that is sufficient to provide a Plating Reduction onto a zincplated steel lag screw of at least 10%.
 13. A method, comprising:incorporating into an aqueous paint an amount of a triazole selectedfrom the group consisting of benzotriazole, salts of benzotriazole,tolyltriazole, salts of tolyltriazole and mixtures thereof that issufficient to provide a Plating Reduction onto a zinc plated steel lagscrew of at least 10%.
 14. The method of claim 13, wherein incorporatingthe amount of the triazole includes adding sodium tolyltriazole at aconcentration of 1.0 percent active based on latex solids in the aqueouspaint.
 15. A method of reducing plate out of an aqueous coatingcomposition comprising: adding a triazole selected from the groupconsisting of benzotriazole, salts of benzotriazole, tolyltriazole,salts of tolyltriazole and mixtures thereof to a composition comprising:(a) an anionically stabilized aqueous dispersion of a copolymer, thecopolymer comprising in polymerized form a polymerization mixturecomprising two or more ethylenically unsaturated monomers where, basedon the total weight of all ethylenically unsaturated monomers in thepolymerization mixture, from 0 to about 4 weight percent of the monomersare alpha, beta-ethylenically unsaturated aliphatic carboxylic acidmonomers; (b) an effective amount of a polyimine or polyamine; and (c)an effective amount of a volatile base; where the amount of triazole isfrom about 0.01 to about 5 weight parts, based on 100 weight partssolids of the copolymer of (a).
 16. The method of claim 1, wherein thecomposition has a pH greater than about 7.